3,5-Dimethyl-2-thienyl-(n-haloalkylthiocarboxanilide) herbicides

ABSTRACT

Novel 3,5-dimethyl-2-thienylcarboxanilides and 3,5-dimethyl-2thienyl-(N-haloalkylthiocarboxanilides) are active pre- and postemergent herbicides.

United States Patent 1 [45] July 1,1975

Kobzina [54] 3,5-DlMETHYL-2-THIENYL-(N- 3,303,201 2/1967 Stecker 260/3322 E ggkg'gigg FOREIGN PATENTS OR APPLICATIONS 2,011,214 2/1970 France 260/347.3 Inventor: J Koblma, Walnut Creek, 2,006,472 8/1970 Gennany 260/3473 Calif. 1,563,735 4/1969 France 260/3322 [73] Assignee: Chevron Research Company, San

Francisco, Calif. Primary Examiner-Henry R. Jiles Assistant ExaminerC. M. S. Jaisle [22] Filed July 1973 Attorney, Agent, or FirmJ. A. Buchanan, Jr.; John [21] Appl. No.: 383,751 Stoner, Jr.; Raymond Owyang [52] US. Cl. 260/3321 C; 71/90 57 ABSTRACT [51] Int. Cl C07d 63/16 58 Field of Search 260/3322 c, 347.3 Novel 3.5-dimeIhyI-Z-thienYICarbQXanilides and dimethyl-2-thienyl-(N-haloalkylthiocarboxanilides) 5 References Ci are active preand post-emergent herbicides.

UNITED STATES PATENTS 11/1964 Leon et a1 260/3473 3 Claims, N0 Drawings 1 3.S-DIMETHYL-Z-THIENYL-(N-HALOALKYLTHI- OCARBOXANILIDE) HERBICIDES DESCRIPTION OF THE PRIOR ART British Pat. No. 1.215.066, published Dec. 9, 1970, discloses fungicidal 2-thienylcarboxanilides, such as 3 methyl-2-thienylcarboxanilide.

French Pat. No. 1,563,735, published Apr. 18, 1969, discloses herbicidal, nematocidal and fungicidal trichloro-2-thienylcarboxanilides. such as 3,4,5-trichloro-2- thienylcarboxanilide.

Chemical Abstracts. 72, 316132 (1970); 73, 98779;- (1970); 73, 98933m (1970); 73, 108740n (1970); and 76, 46068a (1972). disclose pesticidal furylcarboxanilides and furylcarboxamides.

DESCRIPTION OF THE INVENTION The thienylcarboxanilides of the invention may be represented by the following formula (I):

wherein R is hydrogen, lower alkyl or polyhaloalkylthio of l to 2 carbon atoms and 3 to chloro or bromo groups and Ar is phenyl or 2-fluorophenyl.

Representative lower alkyl groups are methyl, ethyl, n-propyl. isopropyl and butyl. Representative polyhaloalkylthio groups are trichloromethylthio, bromodi chloromethylthio. 1,l,2,Z-tetrachloroethylthio, 1.2,2,2-tetrachloroethylthio and pentabromoethylthio.

The preferred R group is hydrogen or polyhaloalkylthio. Particularly preferred polyhaloalkylthio R groups are polychloroalkylthio, especially trichloromethyl and tetrachloroethyl.

The preferred Ar group is phenyl.

Illustrative compounds of Formula I are:

3,5-dimethyl-2-thienylcarboxanilide 3.5-dimethyl-2-thienyl-(N-methylcarboxanilide) 3.5-dimethyl-2-thienyl-(N-propylcarboxanilide) 3,4-dimethyl-2-thienyl-(N-trichloromethylthiocarboxanilide) 3,5-dimethyl-2-thienyl(N-1,l,2,2-

tetrachloroethylthiocarboxanilide 3.5-dimethyl-2-thienyl-(N-2-fluorophenylcarboxamide) 3.5-dimethyl-2'thienyl-(N2fluorophenyl-N-methylcarboxamide) 3,5-dimethyl-2thienyl(N-2fluorophenyl-N- trichloromethylthiocarboxamide) and 3.5-dimethyl-2-thienyl-(N-Z-fluorophenyl-N-l,1 2,2-

tetrachloroethylthiocarboxamide.

The compounds of the invention wherein R is hydrogen or lower alkyl are prepared by reacting methyl 3,5- dimethyl-2-thiophenecarboxylate with a magnesium iodide derivative of aniline or 2-fluoroaniline, as depicted in the following equation (1):

C11 cocn Arl-lll-lgl wherein R is hydrogen or lower alkyl and Ar has the same significance as previously defined.

The reaction depicted by equation (1) is conducted by reacting substantially equimolar amounts of the methyl 3,5-dimethyl-2-thiophenecarboxylate and the magnesium iodide derivative of aniline or 2- fluoroaniline in an inert solvent at a temperature of 0 to 50C. If desired, one to two molar excess of the magnesium iodide derivative may be employed. The product is isolated and purified by conventional procedures such as filtration, extraction, chromatography, etc.

The methyl 3,5-dimethyl-2-thiophenecarboxylate reactant is a known compound and is prepared as described in German Pat. No. 1,088,507 [Chem Abst. 56, 456 (1962)]. The magnesium iodide derivative of aniline or 2-fluoroaniline is prepared by reacting aniline or Z-fiuoroaniline with methyl magnesium iodide.

The compounds of the invention wherein R is polyhaloalkylthio are prepared by sulfenylating a 3,5 dimethyl-2-thienylcarboxanilide, as depicted in the following equation (2):

CH C-N-Ar R'SCl S O CH IIN 3 C Ar-l'HCl(2) S CH wherein Ar has the same significance as previously defined and R is polyhaloalkyl of 1 to 2 carbon atoms and 3 to 5 chloro or bromo groups, e.g., trichloromethyl, 1 ,l ,2,2-tetrachloroethyl, etc.

The reaction depicted in equation 2 is conducted by reacting substantially equimolar amounts of the car boxanilide and the sulfenyl chloride in the presence of a basic acceptor. Suitable basic acceptors are organic amines such as pyridine compounds and trialkylamines. Generally, at least one mol of basic acceptor is employed for each mol of sulfenyl chloride. The reaction is normally conducted in a polar organic solvent, such as dimethylformamide, acetonitrile or dimethoxyethane, at a temperature of 0 to 50C. The product is isolated and purified by conventional procedures such as extraction, filtration, crystallization and chromatography.

The preparation of the compounds of the invention is illustrated by the following examples.

EXAMPLES EXAMPLE 1 Preparation of 3,5-dimethyl-2-thienylcarboxanilide A sample of 14.2 g (0.1 mol) methyl iodide was added dropwise to 2.43 g (0.1 mol) magnesium turnings in 30 ml diethyl ether. A solution of 9.31 g (0.1 mol) aniline in 30 ml diethyl ether was then added dropwise to the resulting solution of methyl magnesium iodide. After the reaction mixture was stirred for 15 minutes, 8.51 g (0.05 mol) methyl 3,5- dimethylthiophene-Z-carboxylate and about 100 ml diethyl ether was added to the reaction mixture. The reaction mixture was stirred at reflux for 2 hours and then allowed to stand at about 25C. overnight. 50 ml of water and a small amount of hydrochloric acid solution were added to the reaction mixture to dissolve the magnesium salts. The ether phase was separated, dried over magnesium sulfate and sodium carbonate and evaporated under reduced pressure to give an oil. Unreacted aniline was removed from the oil by distillation at 100C and 0.1 mm of Hg. The oil was then chromatographed on silica gel. Elution with 10% ether/90% hexane gave unreacted methyl 3,5-dimethylthiophene-2- carboxylate. Elution with 100% ether gave the 3,5 dimethyl-2-thienylcarboxanilide product, as a white, fluffy solid, mp. 9810lC. Elemental analysis for C H NOS showed: %S, calculated 13.86; found 13.77.

EXAMPLE 2 Preparation of 3 ,5-dimethyl-2-thienyl-(N-trichlormethylthiocarboxamide) A 4.4-g sample of trichloromethylsulfenyl chloride was added to a solution of 5.0 g 3,5-dimethyl-2-thienyl- (N-trichloromethylthiocarboxamide) in 50 ml dimethoxyethane. A 2.2-g sample of triethylamine was then added dropwise to the solution at C. The reaction mixture was stirred at 0C. for 1 hour and then at about 25C. for one-half hour. The reaction mixture was filtered and the filtrate was evaporated to give an oil. The oil was chromatographed on silica gel ether/90% hexane eluants) to give the product as a tan solid, mp. 82-82.5C. Elemental analysis for C H CI NOS showed: %S, calculated 16.48; found 16.1; %C1 calculated 27.93; found 28.9.

EXAMPLE 3 Preparation of 3 ,5-dimethyl-2-thienyl-(N-Z-fluorophenylcarboxamide) A solution of methyl magnesium iodide was prepared by the dropwise addition of 19.97 g methyl iodide to 3.6 g magnesium turnings in 100 ml diethyl ether. To the solution of methyl magnesium iodide was then added dropwise 12 g Z-fluoroaniline at ambient temperature. The reaction was exothermic. A solution of 12 g methyl 3,5-dimethylthiophene-2-carboxylate in ml diethyl ether was then added. The reaction mixture was heated in a bath maintained at 55C. for 2 hours and then allowed to stand overnight at about C. 50 ml water and a small amount of hydrochloric acid solution were added to the reaction mixture to dissolve the magnesium salts produced in the reaction. The organic layer was separated, dried over a mixture of magnesium sulfate and sodium carbonate and evaporated under reduced pressure. The residue was chromatographed on silica gel (10% ether/% hexane eluant) to give the product as a white solid, mp. 7374C. Elemental analysis for C l-l FNOS showed: %S calculated 12.86, found 12.88; %F calculated 7.62, found 7.58.

UTILITY The compounds of the present invention are, in general, herbicidal in both preand post-emergent applications. For pre-emergent control of undesirable vegetation, the herbicidal compounds will be applied in herbicidally effective amounts to the environment or growth medium of the vegetation, e.g., soil infested with seeds and/or seedlings of such vegetation. Such application will inhibit the growth of or kill the seeds, germinating seeds and seedlings. For post'emergent applications, the herbicidal compounds will be applied directly to the foliage and other plant parts. Generally, the herbicidal compounds of the invention are effective against weed grasses as well as broadleaf weeds. Some may be selective with respect to the type of application and/or type of weed.

The compounds of the present invention can be used alone as herbicides. However, it is generally desirable to apply the compounds in herbicidal compositions comprising one or more of the herbicidal compounds intimately admixed with a biologically inert carrier. The carrier may be a liquid diluent or a solid, e.g., in the form of dust powder or granules. In the herbicidal composition, the active herbicidal compounds can be from about 0.01 to by weight of the entire composition.

Suitable liquid diluent carriers include water and organic solvents, e.g., hydrocarbons such as benzene, toluene, kerosene, diesel oil, fuel oil, and petroleum naphtha. Suitable solid carriers are natural clays such as kaolinite, atalpulgite, and montmorillonite. In addition, talcs, pyrophillite, diatomaceous silica, synthetic fine silicas, calcium aluminosilicate and tricalcium phosphate are suitable carriers. Organic materials such as walnut-shell flour, cottonseed hulls, wheat flour, wood flour, or redwood-bark flour may also be used as solid carriers.

The herbicidal composition will also usually contain a minor amount of a surface-active agent. Such surface agents are those commonly known as wetting agents, dispersing agents and emulsifying agents, and can be anionic, cationic or nonionic in character. The herbicidal compositions may also contain other pesticides, adjuvants, stabilizers, conditioners, fillers, and the like.

The amount of herbicidal compound or composition administered will vary with the particular plant part or plant growth medium which is to be contacted, the gen eral location of application i.e., sheltered areas such as greenhouses, as compared to exposed areas such as fields as well as the desired type of control. Generally, for both preand post-emergent control, the herbicidal compounds of the invention are applied at rates of 0.2 to 60 kg/ha, and the preferred rate is in the range 0.5 to 40 kg/ha.

Preand post-emergent herbicidal tests on representative compounds of the invention were made using the following methods:

Pre-Emergent Test An acetone solution of the test compound was pre pared by mixing 750 mg of the compound. 220 mg of a nonionic surfactant and 25 ml of acetone. This solution was added to approximately 125 ml of water containing l'56 mg of surfactant.

Seeds of the test vegetation were planted in a port of soil and the test solution was sprayed uniformly onto the soil surface at a dose of 33 ,u/cm The pot was watered and placed in a greenhouse. The pot was watered intermittently and was observed for seedling emersenting no phytotoxicity and 100 representing complete kill.

The results (average of 3 tests) of these tests appear in Table I. For comparison, a variety of closely related thienyl carboxanilides and carboxamides were also tested.

In Table l. the following abbreviations are employed:

gence. health of emerging seedlings. etc., for a 3-week 0 Wild Oats (Avena fatua) period At the end of this period, the herbicidal effec- Wamgwss @W a e C Crabgrass (Dlgitaria sangumalls) tiveness of the compound was rated based on the physi- M Mustard (Brussica Mvensis) ological observations. A O-to-lOO scale was used. 0 rep- P Pigweed (Amaranthus retroflexus) resenting no phytotoxicityx 100 representing complete L Lumhsquuner (chenopod'um 111mm) kill.

TABLE I Herbicidal Effectiveness Pre-Emergent/Post-Emergent Compound 0 W C M P L 3.S'dim0th)l-Zthienylcarhoxanilidc 95/0 lO0/O 100/0 95/60 lO0/40 95/60 1 3.5-dimethyl-2-thienyl-(N-trichloromethylthiocarboxanilide) 0/30 0/65 0/20 100/85 95/50 l00/l00 2 3.5-dimcthyl-2-thienyl-(N-2-fluorophenylcarhoxamide) 93/40 100/40 lOO/O lOO/60 100/20 l0O/65 3 4 3-methyl-2-thienylcarhoxanilide 0/0 0/0 0/0 0/0 0/0 0/0 5 3-methyl-2-thienyl-( N-Z-fluorophenylcarhoxamide) 0/0 0/0 0/0 lO/O 0/0 l5/O 6 l mcthyl-l-thienylcarlmxanilidt: 0/0 0/0 0/0 15/0 O/O 0/0 7 4-methyl-2-thienyHN-B-tolylcarboxamide) ()/0 0/0 ()/0 O/O O/O 0/0 8 4-meth \'|-Z thicn \l-(N-Z-fluorophcnylcarboxumide) 0/20 O/ 0/10 0/35 0/20 O/ 9 4 methyl-5 chloro-2-thienyl-( N-2-fluorophenylcarboxamide) 0/0 0/0 0/10 0/25 0/25 0/25 10 4-methyl5-chloro-2-thienyl-( N-4-chlorophenylcarboxamidc) 0/0 0/0 0/0 ()/0 0/0 O/O l l 4-mcthyl-5chloro-Z-thienylcarboxanilide 0/0 0/0 0/0 0/0 0/0 0/0 12 4-mcth \'l-5-chloro-2-thienyl-( N-3-tolylcarboxamide) ()/O ()/0 0/0 O/O O/O ()/0 13 3.4-dimethyl-Z-Ihienylcarboxanilide 0/0 ()/0 0/0 0/0 0/0 0/0 14 3.4-dimethyl-2-thienyl-(N-Z-fluorophenylcarboxamide) 0/0 0/0 0/0 0/0 0/0 0/0 15 2.5-dimethyl-3-thicnylcarboxanilide 0/0 W0 0/() 0/0 0/0 0/0 16 3.5-dimcthyl-2-thienyl-( N-4-chlorophenylcarboxamide) ()/O (J/() 0/0 0/0 ()/0 0/0 17 3.5-dimethyl2-thienyl-( N 3.4-dichlorophenylcarboxamide) 0/ 0/0 0/0 0/0 l S 3.5dimethyl-2-thienyl-( N-3.5-dichlorophenylcarboxamide) 0/0 0/0 0/0 0/0 0/0 0/0 19 3.5'dimethyl-Z-thienyH N-cyclohexylcarboxamidcl /0 0/0 O/O 0/0 20/0 20/0 20 3.5-dimethy|-2-thienyl-( N-p-tolylcarboxamide) 0/0 0/0 0/0 lO/O lO/O l0/0 2] 3.5-dimcth} l-2-thien \'l-( N-methylcarboxamide) 0/0 0/0 0/0 0/0 0/0 0/0 22 4O o a Post-Emergent Test What 15 claimed is:

1. A compound of the formula s o The test compound was formulated in the same manner as described above for the pre-emergent test. The CH cconcentration of the test compound in this formulation 2 was 5000 ppm. This formulation was uniformly sprayed on 2 similar pots of 24'day-old plants (approximately 15 to 25 plants per pot) at a dose of 33 ,u/cm After CH3 the plants had dried. they were placed in a greenhouse and then watered intermittently at their bases, as needed. The plants were observed periodically for phytotoxic effects and physiological and morphological responses to the treatment. After 3 weeks, the herbicidal effectiveness of the compound was rated based on these observations. A O-to-lOO scale was used, 0 reprewherein R is haloalkylthio of l to 2 carbon atoms and of 3 to 5 chloro or bromo groups, and Ar is phenyl or 2-fluorophenyl.

2. The compound of claim 1 wherein R is polychloroalkylthio.

3. The compound of claim 2 wherein R is trichloromethylthio and Ar is phenyl. 

2. The compound of claim 1 wherein R is polychloroalkylthio.
 3. The compound of claim 2 wherein R is trichloromethylthio and Ar is phenyl. 